I am the original owner of my 97 F350 7.3 and never had a days trouble till just recently my truck would just crank and crank and not start unless I removed both positive battery cables then reattach them she fires right up, also it seems as though neither the glow plugs or the plug work anymore. I checked all fuses and they are good any suggestions??????

 

Probably the glow plug relay. Watch and see if your voltage drops when you turn the key to the on posittion but not cranking it. If you have a multi meter check the voltage at the GPR to verify operation.

I don't know about the battery disconect helping...

 

I'm going with the glow plug relay too.
You'll see a pair of them by the right side valve cover.

 

Yes my voltage does drop when I turn on the key as well as my battery gauge seems to be charging all the way over to the L on normal when running thats is unusuall as well

 

its probably not a glowplug system failure since all you do is unhook that batteries then hook them back up. Does the tach move when the engine won't start. if its doesn't you need a cam sensor. Is there a check engine light when the truck won't start?

 

No check engine lights or anything it is the wierdest thing It seems like as soon as the block heater and glow plugs stopped working then it wont start just like it is not getting fuel or something but as soon as I disconnect and reconnect the cables it fires right up

 

do you have a chip or tuner install? any way to get a scanner hooked up to to check for codes that aren't setting the light?

 

No I dont, It really puzzles me up until 1 week ago everything was great I dont know, the only other thing like I said earlier is I noticed the charge indicator charging way up past the L of normal and that was never like that it was always on r .

 

is it still over charging? that could be related to this issue. I would get it started then go get the batteries and alt tested. Then we'll see whats going on. its possible the volatge regulator went out and is not being kind to the computer.

 

Yeah Iam taking it to have that tested tommorow the Alt. is fairly new less than 1 year old. the Batterys are old, I guess that could be the issue I just dont know why that would affect the block heater not working. Or the truck not starting but who knows. thanks for all the input I really apprieciate it. Ill let ya know what happens. I love the truck it has 200K miles on it and up till now it has been the best truck I ever owned

 

Isn't the block heater on a totally separate circuit? Surely these problems are not related...

 

yes the block heater is a stand alone system that just plugs into household power. Why do you say the block heater doesn't work? is it just cause the truck won't start?

do you get any smoke when you crank it but it won't start? if you don't get smoke you are not getting any fuel, ie the injectors are not firing. if you do have smoke then yes we have a glow plug issue.

 

Yes I do get smoke when I crank it, When I plug my truck in at night it would start right up and the wait to start light would go right out in a second. Now the wait to start light stays on for 20 seconds or so. I know the block heater is separate from everything else thats what baffles me why all the sudden this all happened at the same time.

 

ok you do get smoke. then yes you probably have a glow plug problem. It makes no sense that if you unhook the batteries then hook them back up that it starts right up. Have you done that more than once and had it work? If you have an ohm meter to test the block heater here is what you do. touch each lead to one of the flat prongs of the block heater plug. you should have continuity or some where between 1 and 20 ohms or so. I am not sure what the spec is but just report your findings back.

Now test the glow plug relay. with a test light or volt meter turn the key on with the engine cold and you should have power at both big terminals on the relay. or if you don't have a test light or voltmeter use a screw driver and jump the two big terminals just like you would a start solenoid to jump a car. jump them for about 30 seconds to a minute then go try to start the truck. if it starts right up you need a glow plug relay.

 

Okay I just got my batteries tested they are fine as is my alt. so I will try your suggestions. This morning it was 6 degrees when I tried to start my truck, went to turn it over cranked for maybe 3 seconds then it seemed as if the batteries went dead I disconnected them again and reconnected them and it fired right up. I will go out in a bit and do the tests you suggested. The guy at the parts store never heard of that either, Thanks again